Sectionalizers are known in the art of power systems. A sectionalizer is a protective device that automatically isolates a faulted section of line from the rest of the distribution system. A present-day distribution system typically consists of a feeder line originating from a substation. Several lateral lines are tapped off of the feeder. Distribution transformers installed on these lateral lines supply end users. Often, several branch lines are tapped off of a lateral line, which, in turn, supplies power to several end users.
The challenge in the art of electrical distribution systems is to keep outages caused by overcurrents confined to a minimum possible section of the overall distribution system. In the art, the usual practice is to install progressively smaller protective devices, such as fuse cutouts, as the circuit moves away from the substation. However, the art has grown to appreciate that the overwhelming majority of faults on a system are temporary in nature lasting a few cycles to a few seconds. These temporary faults may trigger a fuse cutout to actuate, thereby disabling power to the downstream users on that branch line. Once a fuse cutout actuates, a repair truck must be dispatched to the scene to re-deploy the cutout in order for power to be restored. Given the prevalence of temporary faults, the art developed reclosers.
Automatic circuit reclosers contain circuitry that allows them to differentiate between temporary and permanent faults. The device clears temporary faults and coordinates downstream protective devices to isolate lines with permanent faults. To facilitate this operation, the recloser may work with sectionalizers deployed in cutout bodies. Sectionalizers “count” the number of operations of the recloser that feeds the circuit and opens to break the circuit if a pre-determined number of counts is met, indicating the likely presence of a permanent fault. Sectionalizers thus help avoid the vast majority of electrical outages that would otherwise be experienced if simple fuse cutouts were deployed.
Similar to fuse cutouts, when the sectionalizer actuates, gravity allows it to fall out of engagement and hang from the bottom hinge of the cutout body. This fall is accomplished by the provision of a trunnion positioned in the cutout's bottom hinge. The trunnion is held against its natural bias when the device is in the closed position (occasioned by the sectionalizer being fixed into the cutout). When the sectionalizer releases from the cutout, the trunnion rotates away from the cutout and carries the sectionalizer downwardly to the open position. Thus, on those rare occasions of permanent faults, the sectionalizer will release itself from the cutout hood and hang freely in a manner similar to a fuse tube in a fuse cutout. Also, similarly to the fuse cutout, a worker must be dispatched to the scene to re-deploy the sectionalizer in the cutout body in order for power to be restored downstream in the line.
In re-deploying the sectionalizer, the firing mechanism of the sectionalizer must be reset so the sectionalizer will operate properly upon the occurrence of the next permanent fault condition. Resetting is accomplished by pushing the spring-loaded bottom pin back into the “ready” or “set” position. In order to perform the resetting operation, the sectionalizer and trunnion must be removed from the cutout body by a lineman who then uses a wrench to hold the trunnion while rotating the sectionalizer body in a manner that forces the pin back into the set position. The re-loaded sectionalizer and trunnion combination is then re-inserted into the cutout body and power restored to the branch.
While the ability to reduce up to 95% of power outages through reclosers and sectionalizers is a great advance in the art. The present inventors recognized a need in the art to be able to re-deploy sectionalizers without having to remove them from the cutout and physically manipulate them with one's hands and a wrench.
As recognized by the present inventors, the foregoing highlights some of the problems with conventional sectionalizers housed in cutout bodies. Furthermore, the foregoing highlights the present inventors' recognition of a long-felt, yet unresolved need in the art for a resettable sectionalizer configured for use in a cutout that can be reset without having to remove the sectionalizer from the cutout. In addition, the foregoing highlights the inventors' recognition of a need in the art for a resettable sectionalizer that can be reset without a user having to hold the assembly and manipulate its parts with tools.